The invention relates to a circuit for controlling a printing head with electrodes that are arranged on a slope. This printing head serves for writing on metal paper. It is guided over the paper in print line direction, with the printing head electrodes touching the surface of the metal paper. If a printing voltage is applied at predetermined times the metal paper is burnt out at the contact surface with these activated electrodes, and an optically visible image is obtained.
The information that is to be supplied to the printing head can be stored in a host computer with a main storage. This information is generally stored in such a manner that it can be employed for controlling a printing head with electrodes placed one above the other, but not for a printing head with electrodes arranged on a slope. According to standard considerations the information read out of the main storage column-by-column has to be applied, for a printing head with electrodes arranged on a slope, to said printing head with a delay depending on the respective row of character elements.
The term row of character elements means that a character has a matrix-like structure, i.e. that a character extends over several adjacent columns of elements in one coordinate direction, and over several rows of elements arranged one over the other, in the other coordinate direction.
According to conventional consideration in a metallized paper printer, the controlling of the electrodes on a slope would require shift registers of different lengths which in their number correspond to the number of electrodes (see also detailed explanation of FIGS. 1 and 3). This, however, would involve extensive circuitry.
In order to avoid this disadvantage it is the object of the invention to provide a control circuit for a printing head of a metal paper printer which requires a low amount of circuitry and is universally applicable for printing heads with different electrode staggering.